PMC

Distribution of latencies in the gap condition for healthy elderly (10) and the DLB subjects (10).

Group mean value of peak velocity of primary saccade for each direction in healthy and DLB patients; vertical lines are standard error. Peak velocity is lower for DLB patients for all directions.

Group mean latency of saccades with standard error in gap and overlap tasks, for four directions in healthy elderly and DLB patients; longer latencies of saccades for DLB patients than for healthy elderly for each condition.

Group mean coefficient of variation (CV) in peak velocity of the primary saccade for each direction in healthy and DLB patients. Variability is higher for DLB patients for all directions.

Group mean coefficient of variation (CV) in saccade latency in gap and overlap tasks, for each direction in healthy elderly and DLB patients. Variability is higher for DLB patients for all conditions.

Examples of saccade latencies distribution with trials from some controls and DLB patients in the gap task. The mean values and the variability (standard deviation/mean latency) of saccade latency are presented in the box. All three DLB patients show abnormal long latency.

Group mean gain of primary saccade and of the final eye position for each direction in healthy elderly and DLB patients; vertical lines are standard error; horizontal lines are gain at 1. Gain is lower for DLB patients for all directions.

Group mean peak velocity (with standard error) and its coefficient of variation for saccades of 9° to 11° for healthy and DLB patients; no significant difference of peak velocity between the two groups, yet, coefficient of variation is higher for DLB patients.

Group mean coefficient of variation (CV) in the gain of the primary saccade and of the final eye position for each direction in healthy elderly and DLB patients; variability is higher for DLB patients for all directions.

Typical recordings of horizontal saccade are obtained by averaging the position signal of the two eyes (LE + RE)/2 and their corresponding velocity traces for one healthy elderly and one DLB patient. The arrows “i” and “p” indicate the onset and the end of the primary saccade, respectively; the arrow “f” for the final eye position Figure . Examples of saccade latencies distribution with trials from some controls and DLB patients in the gap task. The mean values and the variability (standard deviation/mean latency) of saccade latency are presented in the box. All three DLB patients show abnormal long latency.

Experimental design. (A) Spatial arrangement. Five white luminous dots (angular size 0.2°) were presented on a black computer screen at 57 cm from the subject (required convergence 6°), one at the center of the screen; the others at an eccentricity of ±10° horizontally or vertically. (B,C) Temporal arrangement. Each trial started by lighting one central dot during approximately 1500–2000 ms. For the gap task, between the fixation offset and the target onset, there was a gap of 200 ms (B); for the overlap task, the fixation stays on 200 ms after the target onset (C). The target, one of the eccentric dots, appears for 1500 ms.